Macular edema produces loss of central vision and is a clinical manifestation of diabetic retinopathy. It is due to retinal microvascular changes, and the pathogenesis is not only related to VEGF dependency but also to other inflammatory and angiogenic cytokine levels that can be suppressed by corticosteroids. (Sohn H J et al. Changes in aqueous concentrations of various cytokines after intravitreal triamcinolone versus bevacizumab for diabetic macular edema. Am J Ophthalmol. October 2011; 152(4):686-94.)
Intravitreal corticosteroid injection can be a treatment option for some cases of chronic macular edema not reacting to classic treatment such as laser photocoagulation, periocular and systemic steroids or carbonic anhydrase inhibitors.
Intravitreal corticosteroid injection is also used to treat uveitis and to improve the visual acuity in patients with branch retinal vein occlusion or central retina vein occlusion. However, repetitive intravitreal injection is required to maintain the optimal and efficient corticosteroid concentration in the eye, and this is associated with complications such as infectious endophthalmitis, retinal detachment, traumatic cataract and increase intra-ocular pressure (IOP). One study shows the incidence of increased IOP after intravitreal steroid injection was 57.69% at one month, and 75 and 47.05%, at 3 and 6 months, respectively and progression of cataract was found in 22.72% of the patients. (García Fernández M et al. Intravitreal triamcinolone acetonide use in diffuse persistent diabetic macular edema. Arch Soc Esp Oftalmol 2011 October; 86(10):314-319.)
In view of the deficiencies outlined above, there is a need for intravitreal steroid injection with reduced side effects.